Wireless LOS Terminology

November 28, 2013 at 10:00 AM

Why Line of Sight (LOS) is so important

 

Sample of LOS and Fresnel Zone Diagram

When designing an outdoor wireless network, ask yourself this: what is between point A (antenna 1) and point B (antenna 2)? This path between two antennas is referred to as the Line of Sight (LOS).

 

There are three main categories of Line of Sight. Full Line of Sight (LOS) is where no obstacles reside between the two antennas. Near Line of Sight (nLOS) includes partial obstructions such as tree tops between the two antennas. Lastly, Non Line of Sight (NLOS) is where full obstructions exist between the two antennas.

 

By determining the specific Line of Sight conditions in the WiFi network area you can then determine the correct type of wireless system to install.

 

Another common term to be aware of is The Fresnel Zone, referenced in the diagram above. It is is an electromagnetic phenomenon where light waves or radio signals get diffracted or bent from solid objects near their path. The radio waves reflecting off the objects may arrive out of phase with the signals that traveled directly to the receiving antenna, thus reducing the power of the received signal.

 

Line of Site (LOS) Overview Diagram

Print and post the above diagram.

 

For indoor wireless network installations it is important to consider obstacles such as walls, ceilings, and furniture that will affect Line of Sight since these all play a role in wireless signal reception. In wireless transmissions, reflections (when wireless signals "bounce" off objects) and multipath (when wireless signals travel in multiple paths arriving at the receiver at different times) are as important as signal strength in determining the success of an installation. A signal will also exhibit peaks and nulls in its amplitude and alteration of its polarization (vertical or horizontal) when propagating through walls, ceilings and reflecting off metallic objects. 

 

Path Loss is another area of concern when dealing with Line of Sight. For instance, although 2.4 GHz signals pass rather well through walls, passing through trees and leaves is a challenge. This is due to the difference of water content in each. Radio waves in the 2.4 GHz band absorb into water very easily, so the high level of moisture in trees or leaves would trap the waves. When faced with nLOS or NLOS conditions due to trees, 900 MHz is your best choice as it is not absorbed like 2.4 GHz.

 

 

Click here to shop L-com’s Hyperlink brand wireless products.

  

How to Extend the Range of Your Wireless Signal

September 4, 2013 at 10:00 AM

 

 

One of the most common questions we are asked is: "How do I extend my WiFi signal?" Whether you need extension for an indoor or outdoor application, here are your options:

 

Use a higher gain antenna: By using a higher gain antenna you can extend your wireless signal range, though one thing to consider when using a higher gain antenna is potential loss of vertical signal coverage. Typically when you increase the gain on an antenna the RF gain pattern becomes more focused and produces a narrower horizontal beam. Read more about this phenomenon of higher gain causing less vertical signal coverage.

 

Add a WiFi amplifier: By adding a WiFi amplifier you can boost your wireless signal. We suggest trying one of our WiFi booster kits that are available for purchase by anyone in the United States without the need for a special FCC license. These kits offer easy set up and strong signal extension and coverage capabilities. Additionally we offer RF amplifiers for export, military and FCC licensed users supporting frequencies ranging from 900 MHz to 5.8 GHz.

 

Upgrade from 802.11b/g to 802.11n: If you are currently using 802.11b or 802.11g access points and wireless adapters, consider upgrading to the latest IEEE standard, 802.11n. 802.11n offers better range and speed than 802.11b and 802.11g standards products.

 

Use a higher power Access Point: A typical WiFi router or Access Point provides about 30mW of transmit power. By upgrading to a higher power access point or router you can boost your wireless signal resulting in extended coverage.

 

As with any wireless installation, Line of Sight and the Fresnel Zone must be considered along with other factors such as multipath interference. These phenomena and your physical environment (obstacles, obstructions etc.) all affect your signal strength and range.

 

WiFi Antennas WiFi Amplifiers WiFi Access Points
WiFi Antennas WiFi Amplifiers WiFi Access Points

 

By using one or a combination of these aforementioned upgrades and additions you can provide greater wireless signal coverage. Good luck!

 

Access Point (AP) Antenna Replacements

August 21, 2013 at 10:00 AM

 

Upgrading the antennas on your WiFi access point: How to determine the correct AP connector

 

Our technical support department often answers questions like: "How do I upgrade my access points' antennas?" or "How do I identify the type of connector on my WiFi access point or router?" There are a few simple steps to adding or replacing the antenna on your wireless product.

 

First you must check to see if the antennas on your access point are removable.

 

                               Front of an EnGenius wireless access point (AP) showing antennas behindBack of an EnGenius wireless access point (AP) showing antennas

Front and back of a WiFi Access Point showing removable rubber duck antennas installed

 

Back of an EnGenius wireless access point (AP) showing antennas removed

Back of a WiFi Access Point showing rubber duck antennas removed.

 

Next you should identify the type of connector the antenna jack is on the access point. One tip is to check with the manufacturer's website or user manual for your specific make and model listing for the antenna connector type. If you cannot find it on the manufacturer's web site, you can compare it with our common RF connector chart shown below.

 

Common RF Coaxial Connectors

 

Also, you may want to upgrade to a higher gain rubber duck antenna on your access point to increase the signal range and strength. View our 2.4 GHz Rubber Duck antenna selection.

 

Or you might want to connect your access point to an outside antenna. In this case you will need to connect a low loss coax pigtail cable to your access point and then to a longer antenna feeder cable to reach the outside antenna as illustrated below.

 

Illustration of low loss coax pigtail used to connect wireless AP to an antenna

Quick tip: If you need a new antenna, try L-com's Antenna Product Wizard to make your search easier. The wizard will walk you through three steps to identify antennas that match your criteria.

What Does MIMO Mean?

August 7, 2013 at 10:00 AM

Multiple-in/Multiple-out Antennas (MIMO) Explained

 

MIMO Panel Antenna Showing Multiple Coaxial Lines

Most antennas have worked very simply: a frequency transmitted from one antenna could be picked up by a antenna tuned to receive it a distance away without the need of cables between them. While this basic description of a wireless system works, today we have many ways to improve upon the basic concept to increase things like redundancy and coverage. One of those methods is MIMO, which stands for multiple-in multiple-out.

 

MIMO antennas are actually several antennas all within a single physical item or radome. They co-exist either by working in different bands (as the IEEE standard 802.11n works, in both 2.4 GHz and 5.8 GHz) or different polarities, or both. By breaking the data into separate signals and broadcasting them over multiple antennas, MIMO systems can pick from the strongest signal no matter what the environmental conditions.

 

If you have a radio, access point, router or other wireless device that uses MIMO transmission, you will usually see separate jacks for the different signals. Likewise, a MIMO antenna will have multiple jacks or cables to hook up. Once they are plugged in, the antenna takes advantage of a phenomenon called "multipath", which refers to the way multiple signals bounce off of objects and arrive at the receiver at slightly different times.

 

Quick note: L-com's HyperLink® MIMO antenna product center includes options for many popular bands and antenna types.

How to Install Grid Antennas

July 24, 2013 at 10:00 AM


Grid Antenna Mounted on a Mast or Pole with Downward Angle

To make installation for your application easier, here’s a rundown of what to look for. First though, let’s decipher this: why use a Grid Antenna?

 

For point-to-point communications, a grid antenna has a lot of advantages that may make it the best choice for your application. First- since they are directional, they can provide better gain by focusing the beam in a particular direction. Second, though they are typically larger than other antenna types, they usually break down easily to fit in a box for easy transport to the installation site, or for storage while not being used.

 

Once assembled, the grid provides better wind loading than dish antennas. They are very also very easy to mount in either vertical or horizontal polarization and easy to tilt for precise aiming.

 

 

Assembly

 

We suggest double-checking the quality of the antenna before you purchase, especially if the installation is outdoors. The grid should have a UV protective coating and all of the hardware should be stainless steel.

 

When you order a grid antenna, it usually comes disassembled. Different manufacturers make grid antennas with slightly different installation instructions. When putting the grid antenna together, take all normal safety precautions to avoid coming into contact with dangerous electrical lines, etc., then go over the parts list. All grid antennas need the grid itself (often broken into two halves to reduce shipping costs), mounting "L" bracket, mast clamps, hardware such as screws, nuts and washers, and the feed horn. The feed horn is the long, protruding piece in the center of the grid that sends the actual signal. The below video (or this tutorial) demonstrates step by step assembly of the grid antenna. 

 

 

Where can you find a reliable antenna? L-com's HyperLink® line of grid antennas features tons of options for 2.4 GHz and 5.8 GHz bands, along with specialty versions for the 900 MHz, 1.9 GHz, 3.5 GHz and 4.9 GHz. Many options are available in convenient 5-packs that save you time and money. There are also hardware packages for replacing or maintaining components of a grid antenna.
 
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